It has been known for quite some time that ferroresonant reactor devices are useful in regulating line voltage and in providing desired sinusoidal waveforms. For example, Karl I. Selin describes in a paper entitled, "The Polyunit Saturable Reactor", Trans. AIEE (Power Apparatus and Systems), vol. 75, Oct. 1956, pp. 863-867, how a saturable reactor having a load current waveform can be used to deliver a sinusoidal output waveform. Also Selin and A. Kusko in a paper entitled, "Experimental Characteristics of the 3-phase Polyunit Saturable Reactor," Trans. AIEE (Power Apparatus and Systems), vol. 75, Oct. 1956, pp. 868-871, describe how reactor units can be made to saturate and unsaturate in a prescribed sequence throughout the cycle of line frequency. Therefore, a polyphase current drawn by the reactor from a source can be shaped to have a nearly sinusoidal waveform.
It is also well known that in computer applications and data processing applications, it is necessary to isolate the load provided by the computer and data processing applications so that aberrations in the power supply wave shape do not result in computing or storage errors. It is also important to provide continuity of power from the power supply so as not to require a shut down in the computer or data processing applications.
In a recently issued patent to Powell U.S. Pat. No. 4,305,033 issued Dec. 8, 1981, it is proposed to recreate a waveform with a synthesizer network and a separate primary winding means. In that device, a separate set of primary windings is coupled with a set of input chokes and magnetically associated with ferroresonant reactor means used to produce the synthesized waveform. This not only requires the winding of primary and secondary windings on the same iron core member along with the input choke windings but also requires the use of shielding means such as Faraday shields between the primary and secondary windings to prevent the transfer of common mode line noise therebetween. The Faraday shields themselves are then grounded. This construction necessarily increases the size of the iron core on which the windings are wound and results in an unusual amount of core losses. These core losses are especially noticeable when variable loads are incurred. This system, furthermore, does not generate a neutral or reference output so that a grounding transformer is required.